Gelatin has long been used to form films useful in the preparation of soft capsules. It is a hydrolyzed protein from collagen usually obtained by boiling animal bones and cartilage under pressure with water. However, the use of gelatin suffers from several commercial drawbacks; e.g., its animal origins often preclude its availability to those who cannot or will not take animal derived capsules and recent concerns over bovine spongiform encephalopathy, BSE, or “Mad Cow Disease.”
As a result, academia and industry have been trying for many years to develop alternatives to gelatin that can desirably use many of the machines and processes, such as rotary dies, that are already in place to make soft capsules from gelatin alternatives.
For example, Japanese Patent Application Kokai Publication No. 61-10508A discloses capsules made from the composition of polysaccharides including at least carrageenan and polyhydric alcohols. Carrageenan can be used wholly or partly with other polysaccharides such as tamarind gum, pectin, gelatin, alginates, agar, furcellaran, cellulose derivatives, locust bean gum, and guar gum. Polyhydric alcohols include sorbitol, glucose, sucrose, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butane diol and glycerin. The soft capsules are made from concave stamping dies.
Japanese Patent Application Kokai Publication No. 63-164858 discloses mixtures of polysaccharides and polyhydric alcohols with/without alkaline substances. The broad list of polysaccharides purported to be useful in the application include natural polysaccharides such as carrageenan, alginic acid, alginate derivatives, agar, locust bean gum, guar gum, tamarind seed polysaccharides, pectin, xanthan gum, glucomannan, chitin, pullulan and cyclodextrine. The polysaccharides are stated to be combined with a concentrated water solution of at least one of a polyhydric alcohol, sugar alcohol, monosaccharide, disaccharide and oligosaccharide. The mixtures are stated to be useful in forming hulls of soft capsules. The three examples are directed to making hulls of soft capsules having double layers of the mixture with gelatin and a single layer consisting of the mixture of the invention with gelatin. No specific carrageenans are mentioned.
U.S. Pat. No. 5,089,307 discloses heat-sealable edible films comprising at least a film layer containing a water-soluble polysaccharide as the principal component, a polyhydric alcohol and water. The films are stated to be useful for sealing and packaging materials for dried foods, oily foods and the like. The polysaccharides purported to be useful include alginic acid and its salts (such as sodium salt); furcellaran; carrageenan such as kappa-, iota- and lambda-carrageenans; agar; pectin such as high-methoxy and low-methoxy pectins; gums such as tamarind seed gum, xanthan gum, guar gum, tara seed gum, locust bean gum; pullulan; chitin derivatives such as chitosan; starch such as wheat, corn and potato starches; dextrin; edible water-soluble cellulose derivatives such as carboxymethylcellulose; and mixtures of the foregoing. The weight ratio of the polyhydric alcohol to polysaccharide is preferably used in an amount of 1:5 to 1:1, and the polysaccharide is present in an amount of not less than 50% of the total amount of active components. There is no disclosure that such films can be used in the manufacture of soft or hard capsules.
U.S. Pat. No. 6,331,205 discloses aqueous viscous compositions for making soft or hard capsules containing carrageenan, preferably, iota carrageenan as the single gelling agent. Iota-, lambda-, mu-, and nu-carrageenans are disclosed as the types of carrageenans that can be used in the invention, and such are stated to be extracted from a variety of different seaweed sources depending on the extraction method utilized. Plasticizers are disclosed such as those belonging to the polyoxyls class; e.g., glycerol, sorbitol, maltodextrins, dextrose, mannitol, xylitol, polyoxyethylene glycol 400 to 6000, natural glycerides and hemisynthetics and their derivatives, etc. Soft capsules are said to be obtained by an adaptation of the “Scherer” method. Films made from kappa carrageenans are said to have syneresis causing problems in the manufacturing of hard and soft capsules. There is no description of any specific iota carrageenans, kappa carrageenans, kappa-2 carrageenans, etc.
U.S. Pat. No. 6,214,376 discloses gelatin-free capsules made from compositions comprising water-soluble hydrophilic colloidal layers comprising gel films of kappa-carrageenan and a plasticizer. The gelatin free soft capsules are said to be made from kappa-carrageenan as the main gel-forming polymer (at least 50% by weight of gums that form thermoreversible gels or contribute to the formation of thermoreversible gels). Hydrolyzed starches such as maltodextrin may be added to increase solids concentration, aid heat sealing and prevent hazing induced by gelling salts. Other types of gums, such as iota carrageenan, are taught to be minimized, most preferably, to an amount less than 0.5% of the total film composition.
U.S. Pat. No. 6,340,473 requires the use of a modified starch having a hydration temperature below about 90° C. and iota carrageenan for the manufacture of soft capsules using rotary die encapsulation apparatus. The weight ratio of the modified starch to the iota carrageenan is stated to be crucial to forming a satisfactory film. That is, the weight ratio of the modified starch to the iota carrageenan is said to be 1.5:1. The inventors purportedly found that iota-carrageenan alone does not produce an acceptable film and that modified starch alone does not produce an acceptable film useable for encapsulation. The stated theory is that the iota carrageenan functions as an elasticizing agent rendering an otherwise inelastic, modified starch film, elastic. Carrageenans are stated to be complex with hundreds of different products on the market having different functionalities. Eucheuma spinosum is stated to be the seaweed source for iota carrageenan, and not all carrageenans are stated to be useable in the invention, e.g., kappa carrageenan is stated not to be a substitute for iota carrageenan therein.
It is known that certain high solids, low moisture film forming compositions containing, for example, hydrocolloids, form highly viscous solutions that make formation of hydrated films difficult to obtain. The present invention provides a process for preparing high solids, low moisture films from such highly viscous solutions.
In addition, many attempts have been made to make soft capsules from high solids, low moisture films such as hydrocolloids. However, such attempts to make soft capsules have suffered from the drawback mentioned above. That is, hydrocolloids are known to form highly viscous solutions that are difficult to sufficiently hydrate and form a film in conventional soft capsule making processes. The process of the invention therefore allows for the manufacture of soft capsules from such films.